Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

With no annotations provided, the description carries the full disclosure burden, and it handles this well: it discloses the mutation side effect (adds a site), the return value (tracking snippet to install), and the resulting state transition (pending until verified). It does not cover failure cases, idempotency, or re-adding an existing domain, so it is not a 5.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

Two sentences with zero waste: the action is front-loaded, and the second sentence packs both the return value and the state behavior into one efficient clause. No filler or redundant restatement of the tool name.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a single-parameter creation tool with no output schema, the description is nearly complete: it covers the action, the return value (tracking snippet), and the post-call state (pending). The only meaningful gap is not explicitly telling the agent to use verify_site as the follow-up step, though the pending-until-verified wording strongly hints at it.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 100%, so the baseline of 3 applies. The single domain parameter is already fully documented with a concrete example (example.com) in the schema; the description adds no parameter-specific meaning, but at full coverage it does not need to.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

"Add a website to the account" states a specific verb and resource with no ambiguity. It naturally distinguishes itself from all siblings, which are read/analysis operations (get_*, list_*) or the later verification step (verify_site). An agent can tell this is the creation mutation within the tool family.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

The phrase "the site stays pending until verified" implies the add-then-verify workflow and hints that a separate verification step is needed, which maps to the sibling verify_site. However, it never explicitly names the alternative or states when not to use this tool, so the guidance remains implied rather than direct.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.